.png)
CaliciX™ is a feline-specific oral antiviral developed for cats with feline calicivirus (FCV). Each capsule contains 15 mg of EIDD-1931, the active metabolite of molnupiravir, formulated for cats rather than split from a human tablet.
About feline calicivirus (FCV)
Feline calicivirus is one of the most contagious infections cats encounter. Alongside upper respiratory signs, it causes painful ulcers in the mouth, and when the infection becomes chronic it leaves inflammation that never quite settles.
Common signs:
- Ulcers on the tongue, hard palate and lips
- Severe gum inflammation
- Drooling
- Bad breath
- Approaching the food bowl and walking away without eating
- Reduced appetite and weight loss
How it works
EIDD-1931 is phosphorylated inside the cat's cells to its active form and incorporated into viral RNA during replication. Each round of copying accumulates mutations until the virus can no longer produce viable particles. Unlike pain relief and anti-inflammatories, which manage the consequences, this acts on the virus itself.
Treatment reference
- 87% success rate reported in the clinical literature
- One capsule per 2.5 kg body weight, every 12 hours
- Oral only, no injections, given at home
Before you start
Not every case of stomatitis or gingivitis in cats is caused by feline calicivirus. Have your cat examined and other causes ruled out before starting CaliciX™. Dose and duration are set by your veterinarian.
CaliciX™ 15 mg | Feline calicivirus (FCV) antiviral capsules
Active ingredient
EIDD-1931 (β-D-N4-hydroxycytidine) 15 mg per capsule Pharmacologically equivalent to more than 60 mg of molnupiravir (EIDD-2801)
Indication
Management of severe oral inflammatory disease associated with chronic or high-viral-load feline calicivirus.
- Feline chronic gingivostomatitis (FCGS), particularly where calicivirus involvement is confirmed or strongly suspected
- Juvenile-onset gingivitis and stomatitis
- Caudal stomatitis
- Ulcerative stomatitis
- Viral glossitis and lingual ulceration
- Multifocal buccal, labial and palatal ulcers
Clinical signs addressed
Oral pain and reluctance to eat, drooling, halitosis, difficulty swallowing, mucosal ulceration, gingival bleeding, and weight loss driven by oral pain.
Mechanism of action
EIDD-1931 is the intracellular active metabolite of molnupiravir. After absorption it is phosphorylated to the triphosphate form and incorporated into viral RNA by the RNA-dependent RNA polymerase (RdRp). This drives lethal mutagenesis, rapidly reducing viral replication and lowering viral load in mucosal tissue.
Compared with EIDD-2801 (molnupiravir):
- Higher antiviral activity
- More predictable pharmacokinetics
- No enzymatic conversion from a prodrug required
Reference data show EIDD-1931 to be 4.4 to 10 times more potent than molnupiravir. Source: https://pmc.ncbi.nlm.nih.gov/articles/PMC9227765/
Pharmacokinetics
- High oral bioavailability in cats
- Rapid intracellular activation
- Good distribution into oral mucosa, gingival tissue and saliva
- Stable therapeutic concentrations on twice-daily dosing
- High potency means a lower dose per kilogram
Safety
Contraindications:
- Pregnant queens and cats intended for breeding (theoretical teratogenic risk)
- Severe hepatic impairment
- Caution in cats with reduced renal function, particularly alongside NSAIDs
Monitoring:
- CBC every 2 to 4 weeks where treatment exceeds 6 weeks
- ALT/AST where concurrent medication is in use
- Weight and pain scoring
Adverse effects are usually mild and dose-dependent (gastrointestinal upset, transient lethargy).
Regulatory status
This product is not licensed for use in cats. It is intended for off-label veterinary use under professional supervision and requires informed owner consent.
Expected clinical course
- Drooling and oral pain improve: 3 to 7 days
- Ulcers reduce: 1 to 2 weeks
- Appetite and weight recover: 2 to 3 weeks
- Mucosal healing and reduced inflammation: 4 to 12 weeks